By way of background of the art, there is the invention described in Patent Literature 1. The software testing tool for plant control described in Patent Literature 1, includes: an auxiliary storage device 4 that stores a plant control software 2 for installing into a control panel 21 used for controlling a plant 20, and a test program 3 for testing the health of the plant control software 2 by simulating the actual control panel 21; a calculation device 7 for reading the test program 3 out of the auxiliary storage unit 4 to perform a test process; a display device 5 which is an interface between the calculation device 7 and a person; an input device 6 similarly used as an interface; a storage device 8 for storing calculation results and the software; and a printer 9 for printing the calculation results. Further, Patent Literature 1 also discloses a malfunction influence evaluation method. In other words, in the software testing tool for plant control, it is disclosed that the calculation device includes an influence evaluation means for performing influence evaluation, when a malfunctioning part of the controller and equipment is indicated, to determine how far the indicated controller and equipment are affected.